An apparatus for supplying sheets to a printing machine

ABSTRACT

An apparatus for supplying sheets to a printing machine having a sliding work plane moving in outward and return runs, so as to subject one or more sheets thereon to printing, a station, in which the work plane pauses, being provided with a gripper for transferring the sheets from the apparatus to the work plane, with the work plane paused in the station. The apparatus includes a gantry bearing a loading plane positioned by a side of the pause station and made vertically mobile from a first variable-height operating position, and a second fixed operating position flanking the pause station. A receiving station of a stack of sheets is positioned by a side of the gantry opposite the work plane, the height of the head sheet of the stack defining a first operating position. A gripper, borne by the work plane, with the work plane in the operating position grips the head sheet of the stack and transfer it onto the work plane.

DESCRIPTION OF THE PRIOR ART

Machines are known for printing combinations of writings and/or logos and/or designs on sheets, in particular panels, comprising (see FIG. 1) a work plane L sliding longitudinally, in outward runs N1 and return runs N2, so as to subject one or more panels, arranged thereon, to the action of printing means; the printing is defined after a predetermined number of the runs.

The work plane includes an area useful for printing, defined by a longitudinal height (i.e. in the movement direction of the plane) and a transversal height; this useful area receives either a panel or a plurality of panels, longitudinally flanked.

The following relates to a single panel, though it is understood that depending on a length thereof also two or more panels can be treated.

The loading and unloading of the panels onto and from the work plane is done in pause stations of the work plane.

The present invention relates to apparatus for supplying sheets (e.g. panels) to the work plane.

The known apparatus comprise a loading plane C (see FIG. 1) flanked to the station S in which the work plane L pauses, the height of which is such as to enable gripping means associated to the pause station to grip the panel situated on the loading plane C with the aim of transferring it onto the work plane L.

In a known solution the panel is located manually by an operator on the loading plane; it is clear that the costs attached to the use of manual labour are considerable, also in view of the fact that productivity and reliability tend to diminish due to tiredness.

In a further known solution (see FIG. 1 again) a lift E is used, provided with a table (T) on which the stack(s) P1 and P2-P4 of panels F are arranged.

The lift is activated in step-fashion so as to enable the head panel of the stack to be collected from panel-gripping and transfer means M associated to the loading plane C which position the panel on the loading plane.

There are various drawbacks with the known solution described above.

The size of the lift E reduces the height of the stack P of panels; further, the work of the operators on the loading plane C is made very problematic as the lift E—stack(s) P combination is arranged on the front part of the loading plane C (see FIG. 1).

If two or more panels F are supplied onto the loading plane, a same number of stacks P1-P4 has to be loaded, which have to be freed of their protective coverings, flanked correctly and exhibit a same height so as to optimise the functioning of the panel F gripping and transfer means M associated to the work plane.

It is clear how complex this working system is, and how it involves the use of manual labour.

SUMMARY OF THE INVENTION

The aim of the invention is to provide an apparatus for supplying sheets to the work plane of a printer, which obviates the drawbacks present in the prior art.

A further aim of the invention is to provide an apparatus that is structurally simple considering the performance it offers, plus the fact that it is extremely functional.

BRIEF DESCRIPTION OF THE DRAWINGS

The above aims are attained in accordance with the contents of the claims. The characteristics of the invention are set out in the following with reference to the accompanying tables of drawings, in which:

FIG. 1 is a schematic perspective view of an apparatus of known type, mentioned in the preamble hereto, for supplying panels to a printing machine;

FIG. 2 is a schematic lateral view of the apparatus of the invention;

FIGS. 3, 4 are two perspective views of the apparatus of FIG. 2 which supplies the above-mentioned printing machine respectively with largest-format panels and smallest-format panels;

FIG. 5 is a schematic perspective view of a variant of the conveyor used with the apparatus;

FIG. 6 is a schematic lateral view of the detail I of FIG. 5;

FIGS. 7A,7B are section views of section VII-VII of FIG. 5, relating to the rest configuration and work configuration of a further variant of the conveyor;

FIGS. 8A, 8B are schematic section views of the apparatus of the present invention according to a variant, in different operative configurations;

FIG. 9 is a schematic lateral view of the apparatus of the invention according to a further variant.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the figures, L denotes the work plane of a known printer 100 denoted in its entirety as of known type; as already mentioned, the work plane L is mobile in the outward N1 and return N2 runs, which in FIG. 2 are both perpendicular to the plane of the sheet.

The apparatus of the present invention, denoted in its entirety by reference numeral 10, is arranged by a side of the pause station S of the work plane L.

The apparatus comprises a gantry 1 which supports, with known means 2A, 2B, a work plane 3 constituted by the upper branch 4A of a closed-loop conveyor 4 borne by the gantry; in the illustrated embodiment, the conveyor is constituted by a series of flanked belts 80A, 80B, 80C, 80D, winding on a common drive roller 90A and a common driven roller, not illustrated.

The loading plane 3 is vertically mobile (directions X1, X2), powered by known-type motors (not illustrated).

The conveyor 4 is motorisable (in a known way, not illustrated) in step-fashion, or continuously, so that the upper branch 4A translates in direction Y; note that the longitudinal development of the upper branch is at least equal to the longitudinal height of the work plane L, and the width thereof is at least equal to the width of the work plane L.

A receiving station 70 of a stack 15 of panels 200, 300, arranged on a relative bench 30A, 30B, is located flanked to the gantry 1, on an opposite side with respect to the work plane L.

The depth B of the stack is not greater than the width of the useful area of the work plane L; the longitudinal dimension of the stack 15 is not greater than the longitudinal height of the useful area.

FIG. 3 illustrates the maximum format of the panels 200 on which the printing machine 100 can print; FIG. 4 illustrates a panel format 300 that is smaller than the maximum possible.

The panel 20 gripping and transfer M means, borne by the loading plane 3, are denoted in FIGS. 2-4 generically as they can be made in any way.

The functioning of the apparatus of the invention will now be described.

The operator loads at least a stack 15 into the receiving station 70.

According to the height H of the stack (indicated with a broken and dotted line in FIG. 2) with respect to the reference line “O” (still with reference to FIG. 2), the loading plane 3 is translated so as to be positioned at the head panel of the stack 15; the first operating position K of the loading plane 3 (indicated with a broken line in FIG. 2) corresponding to the height H of the stack.

The first operating position K is height-variable as it depends on the height of the stack which diminishes with the collection of the head panels from the stack.

The apparatus 1 comprises detecting means of the height of the head panel of the stack 15 and detecting means of the height of the loading panel 3: these means have not been denoted since they belong to the prior art.

At this point the means M are activated, and first grip the head panel of the stack 15 before transferring the panel onto the loading plane 3, more precisely on the upper branch 4A of the conveyor 4.

In phase relation with the completion of the transfer (disengagement of the means M from the panel), the loading plane 3 is newly moved (directions X1 or X2) with the aim of positioning the loading plane 3 optimally, and predeterminedly, with respect to the pause station S of the work plane L, the second operating position Q (FIG. 2) being fixed as it is a function of the height of the work panel L.

This enables the gripping means MP associated to the pause station S of the printing machine to grip the panel located on the upper branch 4A of the conveyor 4 with the aim of locating it on the work plane L of the printing machine (see a step of this operation indicated with a broken line U in FIG. 2).

The transfer of the panel from the upper branch 4A to the work plane L can be optimised according to the variant illustrated in FIGS. 7A, 7B.

This variant includes a series of shafts 50, parallel to one another and located at a same height, each being located at the space 60 afforded between the opposite edges of the upper branches of two adjacent belts; each shaft 50 affords a longitudinal flattening 50A.

The shafts 50 are motorised in synchrony using known systems, and a positioned so as not to interfere with the relative flattenings 50A, and with the shafts in the rest position R, against the topmost panel borne by the belts: see FIG. 7A.

The synchronous rotation of the shafts 50 in direction P (work position W) causes the raising of the panel (which therefore is disengaged from the belts) and the translation thereof (arrow G) towards the pause station of the printing machine: this facilitates the gripping of the panel by the gripping means MP.

The motor means vertically moving the loading plane 3 depend on the detecting means of the head panel of the stack and the detecting means of the loading plane; these means act in combination to define the first K and second Q operating positions.

FIG. 3 illustrates the maximum format of the panels; the head panel 200A of the stack is transferred onto the upper branch 4A of the conveyor 4; in this case the upper branch is not moved.

FIG. 4 illustrates a panel, the format of which is smaller than the maximum format.

The means M position the head panel 300A of the stack 15 on the initial part of the upper branch 4A of the conveyor 4 (position Z1 denoted in a broken line in FIG. 4); in phase relation with this operation, the upper branch 4A translates in direction Y by an amount greater than the longitudinal dimension (i.e. direction Y) of the panel: the conveyor moves in step-fashion.

It follows that a series of panels 300 become arranged on the upper branch 4A (positions Z1, Z2, Z3 . . . ) until all the longitudinal extension of the branch 4A iw covered; this enables transferring the series of panels on the work plane L via the means MP.

Between a transfer and another of panels from the stack 15 to the upper branch 4A, the loading plane 3 translates vertically so as to cyclically be arranged in the first H and second Q operating position: this optimizes the transfers.

A further variant of the conveyor 4 is comprised, which is particularly advantageous, with the conveyor being driven in continuous motion (see FIGS. 5, 6).

With reference FIGS. 5 and 6, 55 denotes abutments positioned transversally to the translation direction Y of the upper branch of the conveyor 4.

Each abutment is constituted by a sort of comb, tines 56 of which are arranged at the spaces 60 and exhibit dimensions such as to freely insert in the spaces.

The downstream abutment 55A is fixed, while the other abutments are made mobile (in a known way, not illustrated) from a lowered position A1 (denoted in an unbroken line in FIG. 6) to a raised position A2 (denoted in a broken line in FIG. 6).

In the raised position A2 the tines 56 constitute a same number of abutments for the panels located on the upper branch of the conveyor and arranged correspondingly upstream thereof; in this situation there is a dragging between the panels and the underlying belts.

In the lowered position A1 the tines 56 do not interfere with the displacement of the panels in direction Y.

With maximum-format panels 200 (FIG. 3), the abutments 55 are maintained in the lowered position A1; it follows that each panel transferred onto the conveyor 4 abuts on the fixed abutment 55A.

With panels 300 having a smaller format than the maximum, for example as illustrated in FIG. 4, the abutments 55 are activated cyclically (lowered position A1 and raised position A2) in phase relation with the activation of the panel gripping and transfer means M, such as to define, for each panel 300, the positions Z1, Z2, Z3 . . . )

In the preferred embodiment of the apparatus one stack alone is used; this enables moving one stack only to the station 70 with all the advantages that this brings.

No lift is included in the last station, which makes available the space which, in the prior art, is occupied by the lift; further, access to the loading plane 3 is facilitated.

As the loading plane is vertically mobile, the gripping of the panel at the head of the stack is optimised as well as transfer thereof onto the loading plane and transfer of the panel or panels from the loading plane to the work plane L of the printer.

In a variant of the invention, illustrated in FIGS. 8A, 8B, 8C, 9, the apparatus further comprises conveyor means 16 having a longitudinal development parallel to the longitudinal development of the loading plane 3, which are arranged on the same plane as the apparatus (in particular, considering a plan view of the apparatus, flanked to the loading plane 3), and which extend upstream of the loading plane 3, to the receiving station 70.

In particular, the conveyor means 16 are conformed and dimensioned so as to support a plurality of stacks 15 of sheets flanked to one another (in particular a plurality of sets each formed by a stack 15 and a relative bench 30A, 30B flanked to one another), and are activatable (stepped or continuously) so as to transfer each stack 15 of sheets from the loading station 160 to the receiving station 70 (in a first advancement direction V, indicated by the arrow of FIGS. 8A-8C, 9).

In other words, with this variant an operator loads, with the aid of known means, each stack 15 of sheets, supported by the relative bench 30A, 30B, on the conveyor means 16, at the loading station 160.

Then the activated conveyor means 16 transfer the stacks 15 of sheets one at a time to the receiving station 70 (see FIG. 8A), in which the sheets are picked up as described above. During the picking-up of the sheets from a stack 15, the conveyor means 16 are clearly deactivated (situation of FIG. 8B).

Once all the sheets of a stack 15 have been picked up by the gripping and transfer means M, the conveyor means 16, newly activated, transfer the empty bench 30A, 30B to an unloading station 161, downstream of the receiving station 70. At the same time, another stack 15 of sheets is conveyed to the receiving station 70 (see in particular FIG. 8C).

This variant advantageously enables optimising the productivity of the apparatus and all the printing system, reducing the times required for the predisposing of the stacks 15 of sheets to the receiving station 70, and also for transferring the benches 30A, 30B once empty from the receiving station 70. The apparatus of this variant can further comprise sensor means 18 (illustrated schematically and visible in particular in FIGS. 8A and 8B), arranged along the extension of the conveyor means 16, downstream of the loading station 160 and upstream of the receiving station 70, so as to detect the conveying of a stack 15 of sheets to the receiving station 70 and for consequently deactivating the movement of the conveyor means 16.

In other words, the sensor means 8 detect the transfer of a stack 15 of sheets to the receiving station 70, and deactivate the movement of the conveyor means 16 so as to enable picking-up of the sheets by the gripping and transfer means M.

This specification advantageously enables further optimising the functioning of the apparatus according to the invention with respect to the prior art.

The conveyor means 16 can alternatively be activated and deactivated manually by an operator, who acts for example on a button (this situation is not illustrated).

In the preferred embodiment illustrated in FIGS. 8A, 8B, 8C and 9, the conveyor means 16 comprise a roller conveyor.

The conveyor means 16 can alternatively comprise two roller conveyors, a first and a second, arranged aligned and adjacent to one another.

The variant described in the following and illustrated in FIG. 9 is especially advantageous in a case of stacks of sheets exhibiting different parameters to one another, such as for example stacks of sheets 15, 15′ of different materials.

In this variant of the invention, the apparatus further comprises a waiting station 162, arranged downstream of the receiving station 70 (and upstream of the loading station 161).

Further, the conveyor means 16 extend from the loading station 160 to the waiting station 162 (therefore beyond the receiving station 70) so as to convey, towards the waiting station 162 (following activation thereof in the first advancement direction V), a stack 15′ of sheets which has reached the receiving station 70 and which must remain in waiting mode before the relative sheets can be gripped by the gripping and transfer means M and transferred to the printing machine 100 (for example a stack 15′ of sheets of a determined material which is to be processed subsequently, as will become clearer in the following).

In particular, the conveyor means 16 are further activatable in a second advancement direction V′, opposite the first advancement direction V (along the same direction) so as to be able to newly transfer the stack of sheets 15′ from the waiting station 162 to the receiving station 70.

According to this variant, the apparatus can further comprise reading means 19, arranged along the extension of the conveyor means 16 (between the loading station 160 and the receiving station 70), so as to verify whether each stack of sheets 15, 15′ is to be conveyed towards the waiting station 162, as will become clearer in the following.

It can occur that two or more stacks 15, 15′ of sheets, each constituted by sheets of different materials, are loaded at a same time on conveyor means 16, so as to be transferred towards the receiving station 70 and therefore be subjected to the printing processes. However, the order in which the stacks 15, 15′ are loaded onto the conveyor means 16 might not coincide with the order in which the stacks 15, 15′ have effectively to be processed by the printing machine 100. Usually, certain printing jobs are performed on sheets of a same material, so that it is necessary to process (or transfer towards a same printing machine 100) the sheets of the same material until the printing job has been completed.

Thus, in a case in which sheets of a first material are in the printing step and a stack 15′ of sheets of a second material is being conveyed to the receiving station 70, this stack 15′ is temporarily transferred (activating the conveyor means 16 in the first advancement direction V) to the waiting station 162, until the processing of the sheets of the first material has concluded. At this point, the conveyor means 16 are activated in the second advancement direction V′ so as to process the stack 15′ of sheets of the second material.

A bar code, for example, can be included on each bench 30A, 30B supporting a stack 15, 15′; the bar code identifies the type of material of the sheets of the stack 15, 15′ supported by the bench 30A, 30B. In this case, the reading means 19 can comprise for example a bar-code reader for conveying, if necessary, the stack 15, 15′ towards the waiting station (i.e. in a case where from a reading of the bar codes it is established that the sheets of the stack 15′ are constituted by a different material from the material of the sheets under process).

FIG. 9 clearly shows the above-described variant, and in particular a stack of sheets 15 of a first type of material is illustrated, the sheets of which are about to be picked up by the gripping and transfer means M, and a further stack of sheets 15′ of a second type of material in waiting mode in the waiting station 162.

This variant is advantageously especially flexible in a case of stacks of sheets 15, 15′ of different materials, as it avoids having to halt the printing process and optimises the total working times.

The above has been described by way of non-limiting example, and any variants, for example in the station 70 two or more stacks can be stationed, are understood to fall within the protective scope of the present invention as described above and as claimed in the following. 

1. An apparatus for supplying sheets to a printing machine, the machine comprising: a work plane sliding longitudinally, in an outward run and a return run, such as to subject one or more sheets, arranged thereon, to action of the printing means; at least a station in which the work plane pauses, provided with gripping means for transferring the sheets from the apparatus to the work plane with the work plane pausing in the station; the apparatus comprising: a gantry bearing a loading plane positioned by a side of the pause station and made vertically mobile, by motor means, from a first operating position, height-variable, to a second operating position, flanked to the pause station; a receiving station of a stack of sheets, located by a side of the gantry on an opposite side with respect to the work plane, at a height of the head sheet of the stack defining the first variable operating position; sheet gripping and transfer means, borne by the loading plane, destined, with the loading plane in the first operating position, to engage the head sheet of the stack in order to transfer the head sheet onto the loading plane.
 2. The apparatus of claim 1, wherein the loading plane is identified in the upper branch of a closed-loop conveyor borne by the gantry, the conveyor being motorisable either in step-fashion or continuously.
 3. The apparatus of claim 2, wherein the upper branch is flanked to the pause station of the printing machine.
 4. The apparatus of claim 1, wherein the motor means are commanded by detecting means of a height of the stack, and by detecting means of a height of the loading plane acting in combination with the defining means of the first and second operating positions.
 5. The apparatus of claim 2, wherein the conveyor is constituted by a series of belts mutually spaced by means of spaces, it comprises further comprising means, arranged in the spaces 60, for disengaging the sheets from the upper branches of the belts.
 6. The apparatus of claim 5, wherein the means comprise: parallel shafts, situated at a same height, of which at least one is situated in a corresponding space, with each shaft affording a longitudinal flattening; activating means for synchronically activating in rotation the shafts such as to define for the shafts a rest position, in which there is no interference with at least an overlying sheet, and a work position for intercepting the sheet with at least the raising thereof such as to facilitate engagement thereof by the gripping means.
 7. The apparatus of claim 2, wherein the conveyor is constituted by a series of belts mutually distanced by spaces, further comprising means, arranged transversally to the upper branches of the belts, mobile from a lowered position, in which they do not intercept at least an overlying sheet involving the upper branches, to a raised position, in which they define a stop for the sheet.
 8. The apparatus of claim 7, wherein the means are comb-conformed, tines of which insert freely in the spaces.
 9. The apparatus of claim 7, further comprising, in the downstream end of the upper branches of the belts, a comb-conformed fixed abutment, tines of which are inserted in the spaces so as to define an abutment for the at least a sheet resting on the upper branches of the belts.
 10. The apparatus of claim 1, further comprising conveyor means having a longitudinal development parallel to the longitudinal development of the loading plane, which conveyor means extend from a loading station, upstream of the loading plane, to the receiving station; the conveyor means being conformed and dimensioned such as to support a plurality of stacks of sheets flanked to one another, and being activatable in a first advancing direction so as to transfer each stack of sheets from the loading station to the receiving station.
 11. The apparatus of claim 10, further comprising sensor means arranged along the extension of the conveyor means, downstream of the loading station and upstream of the receiving station, for detecting conveying of a stack of sheets to the receiving station and consequently deactivating the movement of the conveyor means.
 12. The apparatus of claim 10, wherein the conveyor means comprise a roller conveyor.
 13. The apparatus of claim 10, wherein the conveyor means comprise a first roller conveyor and a second roller conveyor arranged aligned and adjacent to one another.
 14. The apparatus of claim 10, further comprising a waiting station, arranged downstream of the receiving station; the conveyor means extending from the loading station to a waiting station, in order to convey towards the waiting station, following activation of the conveyor means in the first advancement direction, a stack of sheets which has reached the receiving station and which must remain in a waiting position before the sheets can be engaged by the gripping and transfer means, and transferred to the printing machine; the conveyor means being activatable in a second advancement direction opposite the first advancement direction, in order to newly transfer the stack of sheets from the waiting station to the receiving station. 